Abstract
A cerebellar tumor was incidentally discovered on a CT scan of a 14-year-old boy, which was taken after a minor head trauma. The tumor had a large and thick-wall lining cyst, and was not enhanced with a contrast medium. Therefore, it was considered a ganglioglioma rather than a pilocytic astrocytoma. During surgery, the cerebellar cortex surrounding the tumor was found to be swollen. The tumor and the swollen cortex were removed en block. Histological examinations proved it to be a pilocytic astrocytoma associated with an extension to the surrounding leptomeninges. Radiological diagnosis, therapeutic strategy and prognosis of pilocytic astrocytomas with such an extension or dissemination into the subarachnoid space are discussed.
